The present invention relates to a system for the preservation, transportation and dispensing of dyes. The invention also relates to a reservoir and to a dispensing machine particularly suitable for use in the system.
In the field of varnish-, paint-, and ink-production and the like, the use of dispensing machines which provide for the coloring of a neutral, for example, white or transparent, base by the dispensing and mixing of the base with small predetermined quantities of dyes is now very widespread. The dyes are normally stored in reservoirs which are generally mounted in dispensing machines of known type, for example, such as that described in the Applicant's patent EP-0 198 856.
The continuous development of dispensing machines and the developments in the colored-paint production field as a whole, as well as increased user requirements, have brought to light problems with known production systems.
In particular, the filling, refilling or topping-off of the dye reservoirs are particularly lengthy, impractical and wasteful operations in terms of time and wastage of dye. The refill of dye is normally kept, transported and supplied in containers, for example, tins or bottles, the contents of which have to be decanted into reservoirs mounted in the dispensing machines. Upon completion of this operation, which is carried out manually, it can be seen that a certain quantity of dye remains adhered to the internal walls of the containers used for refilling and is thrown away together with the containers. Moreover, during dye-decanting operations, it is often necessary to use auxiliary filling means such as, for example, funnels and the like, to the walls of which a certain quantity of dye remains stuck, this quantity also being unusable and being thrown away upon completion of the topping-off or refilling operations.
The filling of the reservoirs also causes the dyes to be mulsified with air, necessitating the provision of homogenization systems, for example, such as mechanical stirrers, which are mounted inside the reservoirs and have to remain active for quite a long time to allow the air contained in the dye to be expelled. Until this homogenization operation is completed, the dye cannot be dispensed since the presence of air in emulsion modifies its physical properties of volume and specific weight, making accurate dispensing difficult.
Increasing sensitivity to problems of pollution and waste disposal, which is often reflected in very rigorous norms, also makes the treatment of waste products, whether they are containers or dyes, increasingly onerous. The costs of transportation, storage and the disposal of waste products are gradually assuming proportions which are difficult to reconcile with the requirement to produce low-cost paint products for mass consumption.
A further disadvantage of known systems is that, when the quantity of dye in the reservoirs decreases, the film of dye which remains adhered to the internal walls of the reservoirs dries upon contact with air, forming a solid film which tends to break up. The solid particles thus formed mix with the dye, causing a series of quite serious problems ranging from partial obstruction of the ducts of the dispensing machine to contamination of the finished paint product, with obvious disastrous consequences from the point of view of dispensing accuracy and of the quality of the finished colored product. Moreover, if periodic complete cleaning of the ducts of a dispensing machine is not impossible, it is certainly very onerous in terms of cost and unproductive time when the machine is stopped.
The problem of drying inside the reservoirs is noticed particularly and assumes considerable proportions especially with the use of so-called "solvent-free" dyes, the vector fluid of which has a marked tendency to evaporate on contact with air, with consequent precipitation and/or thickening of the pigment. In these cases, the known solutions provide for the use of expensive and complex sealing systems, stirring and recirculation of the dye, which are detrimental to the economical production and use of the machines.
Various solutions have been proposed for solving the problems mentioned above, but none has succeeded in providing a wholly satisfactory and economical solution. The object of the present invention is to solve all of the problems mentioned above simply, cheaply and effectively.